Generally, engines generate rotational force by combustion of fuel, and the remainder of the combustion energy is discharged as heat energy.
Particularly, cooling water absorbs heat energy while it circulates through an engine, a heater, and a radiator and discharges the heat energy to the outside.
When temperature of the cooling water of the engine is low, there is a tendency that viscosity of lubricating oil increases and hence friction force increases, resulting in increase of fuel consumption and that temperature of exhaust gas rises slowly. Thus, it takes a relatively long period of time for activating a catalyst, resulting in deterioration of quality of the exhaust gas.
In addition, time for normalization of function of the heater becomes longer and hence a driver and passengers can feel cold.
On the contrary, if the temperature of the cooling water of the engine is excessively high, knocking occurs. However, if an ignition timing is adjusted to suppress the knocking, performance may be deteriorated.
Moreover, if the temperature of the lubricating oil is excessively high, lubricating action may be deteriorated.
Therefore, there may be applied a single cooling water control valve that controls a plurality of cooling components by means of a single valve, for example, in a manner that a temperature of the cooling water in a specific portion of the engine is kept high and temperatures of the other portions are kept low.
However, the cooling water control valve is formed such that a rotating cam 1 pushes a valve 2 and allows the valve 2 to tilt and move up and down, as shown in FIG. 1. This cooling water control valve has a problem of leakage which occurs by a gap allowing the tilting movement and the valve 2 may be damaged by a shear force due to the tilting movement.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.